Structure of the Lithosphere and Upper Mantle in den Ocean-Continent Transition from SS Precursors

我们建议利用GRSN和Gräfenberg台站记录的大量地震资料来研究具有SS前兆的大陆-海洋过渡过程中的岩石圈和地幔过渡带。在西南太平洋地震非常活跃地区的事件中，SS的弹射点从阿留申山脉、堪察加群岛和日本俯冲带经过北中国克拉通到青藏高原的走廊取样。走廊穿过不同的构造单元，如俯冲带、旧大陆盾、褶皱带和高高原。我们将调查走廊沿线不同地质单元下的岩石圈和地幔过渡，并推断深部的地球动力学过程。我们将寻找更高分辨率的证据，以证明早些时候提出的大陆和海洋之间乃至地幔过渡带之间的结构差异。SS前兆的高分辨率图像还可以揭示俯冲大洋岩石圈与地幔过渡的相互作用，并有助于回答经常争论的问题，即西北太平洋俯冲带下地幔过渡带内板块停滞的规模和程度。我们将尝试利用SS波形数据的短周期内容，并利用CMP叠加和偏移技术等方法进行实验，以获取高分辨率的岩石圈和上地幔图像，提高上地幔不连续面的横向和深度分辨率，进而为利用SS前兆研究岩石圈-软流圈边界等浅层结构创造新的可能性。

We propose to use the large amount of seismic data recorded by the GRSN and Gräfenberg stations to study the lithosphere and mantle transition zone in the continent-ocean transition with SS precursors. SS bounce points from events in the seismically very active region of the southwest Pacific sample a corridor from the Aleutians, Kamchatka and the Japan subduction zone through the North China craton to the Tibetan plateau. The corridor passes different tectonic units such as subduction zones, an old continental shield, a fold belt and a high plateau. We will investigate the lithosphere and the mantle transition beneath different geologic units along the corridor and infer geodynamic processes at depth. We will search for higher resolution evidence for the earlier proposed structural differences between continents and oceans down to the mantle transition zone. High resolution images of SS precursors may also reveal the interaction of the subducted oceanic lithosphere with the mantle transition and serve to answer the often debated question about the scale and extent of the slab stagnation within the mantle transition zone beneath the NW Pacific subduction zone. We will attempt to use the short period content of SS waveform data and experiment with methods like CMP stack and migration techniques to acquire high resolution lithosphere and upper mantle images and to improve the lateral and depth resolution for the upper mantle discontinuities and, further more, to create new possibilities to study the shallower structures such as the lithosphere-asthenosphere boundary with SS precursors.